Dc voltage drop plus conduit deration chart

[Kevin Goodreau]

Is Dc voltage calculation same as AC single phase?? What if I am pulling 3 sub array <15 amps in same conduit approximately 200 feet?? I believe # 10 is okay and 1 1/4" conduit is fine. Southern NM location

 

[broadgage]

In the case of relatively small conductors, the voltage drop calculation is the same for DC or AC, RMS.
Remember that the NEC requires upsizing of PV conductors, since under extreme conditions the PV array may produce more than the design current.

Circuit ampacity should be based on this, upsizing according to code.

Voltage drop is not a code requirement but a design issue, 3% drop at normal current might be a sensible choice, or it may be economic to aim for less loss.
PV is a relatively expensive source of energy, and it may make poor economic sense to waste 3% of it in cable losses.

Often the code required upsizing of wires, results in a very small voltage drop under normal conditions.